Toyota Corolla cleaning electrical contacts


Now that you know that the circuit board is corroded and probably not working, you’re free to experiment to see if you can clean it up. Might as well try wiping it down with contact cleaner or even just alcohol. I do that with remote control boards when the buttons stop working.



There was a lot of corrosion on it, but I cleaned it anyways. Here also white vinegar and salt worked well. Washed off after a minute. Checked each component for continuity. I realize that components are not supposed to be checked while on a board, but, here I just want to know whether they still conduct or not. Most components seemed to be still working,.except for one leg of an IC that fell off due to the corrosion. I even tried to solder a wire to the stub. It didn’t work. Now, it’s official that this module is dead.



It’s really frustrating to run into things you don’t know how to fix. You have my sympathy.



Maybe you have at least found what’s wrong. That in itself would be a victory.



These things used to frustrate me before. Now I look at it as an opportunity to learn new things. It’s mostly what kind of expectations one has and how much you are willing to take a risk that either makes one to pull out their hair or keep moving.

When I started on this project, I told myself what are the best, worse, bad and everything in between-case scenarios. I am trying to get to the best case scenario, but I know fully well that maybe I might have to settle for the 2nd or 3rd case scenario. And that is ok.

I really wish I knew about the occupancy detection system at the time when the car got flooded. At that time, the battery was out. So, this module must not have been electrically damaged. Many people have the false idea that moisture on circuit boards is always bad. It is bad only if electricity is flowing when moisture is introduced. Most components can survive moisture if cleaned quickly. The damage happened after I connected the battery. I could have cleaned the module and reused it. I successfully resurrected the ecu and starter of another flooded car by merely taking it apart and cleaning it. That is another new information that I learned.

Anyhow, I started this thread to pick your brains on your knowledge and experience in the best and cost-effective way of cleaning electrical contacts. Many of you gave detailed information and suggestions. Thank you all for those valuable suggestions and advice. I think the cleaning option on this project is over. I did clean the wiring harness on the srs module. i am not sure yet if it helped or not. I will know once I replace the occupancy detection module. Now, it is changing-out-parts stage, which is what I am going to do. Thank you all.



These kind of problems do make for a good learning experience for the patient technician.

It might be safe to guess that the seat sensors are really okay. Once you replace the damaged module you will see if that is true. If you still have an issue you could compare the resistance readings between the two seat sensors to see what that shows up.



You’re making a lot of assumptions and I believe they are incorrect based on my 40+ years in the industry designing electronic controls for harsh environments. There is a reason they choose the flexible conformal coating for that board vs a thinner hard coating for the SRS and or ECU modules. The result of that corrosion isn’t the choice of coating or the application of it. I can say with reasonable certainty, what happened is the circuit board assembly house did not clean the board properly before encapsulation. That is exactly the kind of corrosion you see from acid based flux residue left on the board. It will eat the pins right off the chips, the pads and traces off the board over time. It doesn’t change the outcome but re-thinking the conformal coating approach should be approached with caution. You can do more harm than good with some of the ideas you proposed…



I’m fairly certain that if the module gets replaced, the sensor(s) will have to be re-calibrated, and you’re most likely going to need a pro-level scanner to do this

Just a heads-up . . . I’m envisioning a possible scenario where the module gets replaced, and no re-calibration takes place, the srs light is on AGAIN, and somebody’s tearing their hair out trying to figure out what could be the problem this time



As far as calibration goes you might look online for a procedure. I did my Town and Country myself. But I think if I remember right, I did have to use a scanner. I do remmember that I had to use specific weights for calibrating the passenger seat.



I have seen a video where they use a 66-lb weight for the calibration. It didn’t look difficult; it’s just a matter of following the on-screen instructions on the scanner. One guy even used two cases of freon, which came up to the calibration weight. I need to ask around for who could do the calibration or let me borrow the scanner.



depends on the auto manufacturer

Some require special weights for re-calibrating, some don’t



Maybe some of you might have seen this repair manual before. I am including a link here for the next clueless Toyota owner who wants to take up the challenge of figuring out what is wrong with their car and fix it themself. It gave me some idea. Might help someone else too.



Got the occupant detection module from a guy on Ebay today. Plugged it in and…the srs light is still on.

Thanks db4690 for the headsup about the srs module reset & weight sensor calibration. I would be worrying about what else could be wrong.The good news is that now the light for occupant detection and the passenger seat belt light works as it is supposed to.

The error code 32 is gone. Code 31 is still there. Will this go if I reset the code with a scanner and do the weight calibration?
Or, is it still pointing to the replacement of the srs module?



I just spent some time on a professional information website, but I can’t cut and paste . . .

Code 31 is also known as B1000 . . . you’re not actually using a scanner to retrieve codes, but you’re using the blink code retrieval method, correct?

Code 31 is “Airbag sensor assembly center malfunction”

So the partial answer is that code 31 appears to be unrelated to the weight sensor calibration, or lack thereof

This sensor that I mentioned appears to be below the center console. There is no mention of any programming or

go ahead and try to clear code 31/B1000 with a scanner, if you have one handy. But I suspect the srs light and the codes are still present, because a current fault is recognized. Modern srs systems typically work in such a fashion . . . there is a check with the ignition on, if everything is fine, the srs light turns off and remains so. If a current fault is recognized, the light will not turn off after the check, and/or the light will turn on with the engine idling.



Today is a good day! I finally fixed the srs error light in my car.

Thank you db4690 for those error codes. It came handy today when I was on the phone with the tech guys at a local Toyota dealer. When I mentioned srs code 31, he told me that he had never heard of it. I asked him if he is kidding me. He said, ‘no’. Then I had to give him the equivalent B code for him to understand. Those guys wanted $175 for an srs module reset. I wished them a wonderful day and hung up the phone. :wink:

For the past few days, I was trying to acquire another srs module and get it reprogrammed for my car. Something funny happened recently as I was contacting several sellers on Ebay about an srs module. One guy had the exact same part# as mine and reasonable price. So, I started asking him questions about the exact condition of the module, like whether it was water damaged or has any other damage. He replied saying, that module is from a car that was never in a crash or had any water damage. I was confused. I asked him why would anyone pull a perfectly working oem part from a car if it is not in a crash or damaged. I even told him that I understand that majority of parts on Ebay comes from cars that got in to an accident. Looks like I spooked him; he replied back saying, the car was somehow sold and he immediately deleted his listing. :slight_smile:

Today I took the car to a local mechanic that I know. My intention was to see if my srs module is good. If it is not, whether another module can be successfully reprogrammed. He connected a scanner to the computer and cleared the srs codes. We were both expecting the error to come. To our surprise, the srs light did not come back. I really couldn’t believe that this ‘hail Mary’ trick worked and my instrument panel is free of srs error lights after 4 years.

I am not claiming that what I did will work for everyone. It just worked for me. What I did is to clean out the corrosion on the srs module and every connectors under the dash and carpet with my special secret formula solvents. :shushing_face: That trick didn’t work on the occupant detection module (one under the seat). I had to replace it with one that I got from Ebay. Although I was expecting to do a weight sensor calibration, I didn’t have to do it.

Lesson learned from all this is; just because your car gets flooded doesn’t mean that it is a gonner. I personally resurrected my other car that got flooded and cleared the srs light from this Corolla. My mechanical skills are next to nothing. My total expenses for fixing the srs error came to less than $30 and several weeks of my time reading and watching related videos. The dealer’s scanner couldn’t communicate with the srs module. They quoted me over $2500 just to replace the srs module and see what else is wrong, with no guarantee of fixing the problem. I wished them a wonderful day and got out of there as fast as I could. :wink:

Before you start throwing parts at your car, try out the basics, like removing the corrosion with household chemicals and sandpaper. You need to be patient if it doesn’t work. If it doesn’t work, try other stuff. I appreciate the input that I got from this forum and I learned a lot of stuff on the way.



Good news! :rocket:

That mechanic that cleared the code with the scanner . . . I presume he got a box of Krispy Kremes as payment?



:smiley: He is a friend.



even more reason for the box of Krispy Kreme’s. :slight_smile:



Friends get donuts AND coffee. Get an extra coffee, and you two can enjoy a couple hours with the food.



For some reason none of my friends or myself like donuts and stuff. Come to think of it, each of us like cooking. And, we never prefer store bought stuff, if we can avoid it. For us, on most weekends we meet at one of our places, fire up the grill and spent the evening catching up and enjoying the food.

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